The Haywire Heart: How too much exercise can kill you, and what you can do to protect your heart

254 Pages·2017·4.6 MB·English

by  Christopher J. Case

A note to readers: Double-tap on illustrations and tables to enlarge them. After
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CONTENTS
List of Illustrations
Preface
Introduction
1
How the heart works
CASE STUDY: Gene Kay
2
The athlete’s heart
CASE STUDY: Jenni Lutze
3
Heart attacks, arrhythmias, and endurance athletes
CASE STUDY: Micah True
4
The evidence
CASE STUDY: Mike Endicott
5
What to look for in yourself
CASE STUDY: Genevieve Halvorsen
6
Getting the news
CASE STUDY: Mark Taylor
7
Addicted to exertion
CASE STUDY: Dave Scott
8
Treatment options for athlete arrhythmia
CASE STUDY: Paul Ernst
9
The takeaway
CASE STUDY: Jason Agosta
Epilogue
Acknowledgments
Notes
Glossary
Index
About the Authors
ILLUSTRATIONS
Figure I.1 Does more exercise mean greater health?
Figure 1.1 Cross-section of the heart
Figure 1.2 Cardiac diastole
Figure 1.3 Atrial systole, ventricular diastole
Figure 1.4 Atrial diastole, ventricular systole
Figure 1.5 The heart’s electrical circuitry
Figure 1.6 Electrical signals travel in a wave through the heart
Figure 1.7 Action potential in a cardiac cell
Figure 1.8 Action potential in a pacemaker cell
Figure 2.1 Structural differences in the normal heart, the athlete’s heart, and a
diseased heart suffering from hypertrophic cardiomyopathy
Figure 5.1 Alcohol consumption and the risk of arrhythmia
Figure 5.2 An ECG trace of one cardiac cycle
Figure 8.1 The QT interval on a normal ECG trace
Figure 8.2 Pulmonary vein ablation
PREFACE
CHRIS CASE
The sun shone bright on the upturned Flatirons rock formations above Boulder,
Colorado. It was another perfect day in a cycling paradise. Lennard Zinn, a
world-renowned technical cycling guru, founder of Zinn Cycles, author of Zinn
and the Art of Road Bike Maintenance, longtime member of the VeloNews
magazine staff, and former member of the US national cycling team, was riding
hard up his beloved Flagstaff Mountain, a popular road that snakes over 4 miles
and almost 2,000 feet above the city. It was a ride he had done a thousand times
before. But on this day, in July 2013, his life would change forever.
Fifteen minutes into his attempt to set a new Strava “king of the mountain”
(KOM) time for the climb in the 55-plus age group, he felt his heart “skip” a
beat. It was something he had felt before, but only at rest. He looked down at the
Garmin computer on his handlebars and noticed that his heart rate had jumped
from 155 to 218 beats per minute (bpm) and stayed elevated. He tapped the
Garmin’s screen. Was the connection bad? He felt fine but eventually pulled the
plug on the attempt, knowing that the distraction had disrupted any chance at a
record.
His heart rate immediately dropped, so he headed down the mountain to
establish a different Strava segment KOM. His training plan called for a very
hard ride, so he went to another climb and did a set of intervals. His ride
completed, he headed home.
Later that day, he called his physician as a precaution. Much to his surprise,
after describing the incident, he was told to head to the emergency room
immediately. Then things took an even more serious turn: After a series of tests,
the ER physician recommended that he be taken via ambulance to the main
cardiac unit of the Boulder hospital for an overnight evaluation.
Despite the initial alarm, his doctors simply prescribed rest. That seemed
easy enough. So easy, in fact, that even though he trusted the cardiologists and
the ER doctor, he ignored the true depth of their warnings. While he obeyed their
calls for rest for a short time, he eventually returned to his usual training plan.
His only concession was that he did not resist when he was asked to wear a
portable telemetric electrocardiogram (ECG) unit that dangled around his neck
(a device known as a Holter monitor); it didn’t disrupt his routine.
What did disturb life and training were the annoying episodes that started to
become more frequent during his intense rides. Now when his heart rate spiked,
he experienced what felt like a flopping fish in his chest.
More upsetting was the phone call in the middle of the night from a faraway
nurse who had been monitoring the ECG readings from his Holter monitor. She
had some shocking news: His heart had stopped for a few seconds. He had to
finally admit that something was definitely wrong.
By October, Zinn could do nothing to eliminate the episodes. He made every
attempt to reduce the stress in his life, but intense riding and racing always
triggered an episode of elevated heart rate and that fish-out-of-water feeling.
After further visits to his cardiac electrophysiologist, he received an official
diagnosis: multifocal atrial tachycardia.
That’s when Zinn ultimately decided to heed the warning he’d been given
and quit racing. He also backed off from riding with intensity or duration. In
doing so, he felt instantaneously downgraded from thoroughbred to invalid. He
altered the very nature of his life, in more ways than one. He was made to face
the reality that he could never do what he used to do in the same way that he
used to do it. He now became interested in maintaining an activity level to
sustain his longevity rather than his fitness or speed.
Life had changed. Forever.
Zinn quickly realized he was not alone. When he began the psychologically
arduous process of coming to terms with his life-changing condition, he reached
out to friends who had been fabulous athletes in their day and who continued to
push themselves well into their 40s and 50s.
The number of friends, colleagues, and former teammates who had had
similar or more severe heart issues was alarming. Far from being an outlier, Zinn
was one among many.
That’s when I, as the managing editor of VeloNews and a friend and
colleague of Zinn, couldn’t help but think there was more to this issue than an
isolated incident on an iconic climb in a cycling-crazed town. Once I heard the
various stories of heart arrhythmias in masters endurance athletes and read the
research literature on the subject, it was obvious that this would make for a
compelling and important article in the magazine. (An arrhythmia is an irregular
heart rhythm caused by a malfunction in the heart’s electrical system. Zinn’s
tachycardia is but one example.)
With the help of many, particularly Dr. John Mandrola, we published
“Cycling to Extremes: Are Endurance Athletes Hurting Their Hearts by
Repeatedly Pushing Beyond What Is Normal?” in our August 2015 issue.
Mandrola’s assistance was critical, as he is a cardiac electrophysiologist from
Louisville, Kentucky, who frequently writes and lectures on the very subject of
endurance athletes and heart health. He has also been a competitive athlete much
of his life and has an arrhythmia himself (atrial fibrillation, which is defined as a
rapid and irregular heartbeat above 300 beats per minute).
The response from readers and members of the media was staggering. Zinn,
in particular, was inundated by letters, e-mails, and phone calls from friends,
colleagues, and strangers. The overwhelming majority of the attention came
from individuals for whom the article was extremely moving or meaningful,
something they could relate to, a story that touched them unlike anything they
had read before. In more than one case, the article changed a life.
There were also some naysayers, to be sure, those who doubted the
connection or took offense at the representation of their cherished pastime and of
exercise in general. It is true that the scientific community is not fully in
agreement on the numerous complex issues involved in heart arrhythmias and
the potential causal connection to lifelong endurance exercise.
Therein lies the very reason for this book. The topic is broad, multifaceted,
complicated, and, in so many ways, extremely important to investigate further.
Another magazine article wouldn’t move the needle very far. We needed a more
thorough exploration. Why now? The explosion in popularity of endurance
sports has coincided with the ability and desire of an active populace to strive for
elite athletic achievements deep into their lives.
Of course, that begs the question: Is exercise good for your heart?
Undoubtedly, it is. In fact, it is undeniably the best medicine there is for
preventing a host of cardiovascular diseases, as well as a multitude of other
diseases. Its documented beneficial results would qualify it as a miracle drug if a
pharmaceutical company could figure out how to bottle it. But even miracle
drugs have a recommended dosage, and vastly exceeding it is not generally
prudent.
Can there be too much of a good thing? Quite possibly—as you’ll soon learn.